The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An aircraft nacelle is intended to surround a turbine engine and to produce the thrust of the turbine engine by channeling the flows generated by the engine. It should also be able to be opened in order to access the engine and its equipment.
Most turbine engine nacelles comprise a fan cowl surrounding the fan case of the engine and a rear body (often a thrust inverter) surrounding the central portion of the engine.
In order to ensure access to the engine and to its equipment, both of these nacelle components generally open in two half portions.
The opening of these cowls or hatches is allowed by means of the presence of hinges, generally mounted on the upper portion of the nacelle, in a so-called 12 o'clock position, along a pylon line, and are maintained closed by a plurality of locks generally mounted along a locking line in a lower, so-called 6 o'clock portion.
It is desirable that after a maintenance operation, the whole of the locks is closed.
For this purpose, it should be possible to ensure in an efficient, safe and rapid way, proper locking of all the cowls which may be opened, of a nacelle prior to any use of the nacelle. Today, in most cases, this check quasi entirely relies on the attention of the mechanic who carries out the locking operation. Consequently, certain maintenance errors have caused a significant number of bad closures of fan cowls, sometimes inducing major events during flights (opening and loss of a fan cowl). A clear indicator of the locking of the nacelle cowls is therefore a significant source for improving safety of flights.
One of the most frequent causes of opening during flight is the partial closing or opening of the cowl locks. In this scenario, it is often difficult during a routine check to notice that one or several locks are badly closed, since the locking of a single lock <<puts into place>> the cowl which from a distance then seems to be properly closed.
Thus, in order to provide an efficient detection system, it should be possible to initiate unlocking or to be able to partly unlock the cowl without the corresponding status indicator displaying an unlocked status.
Of course, such considerations also apply to nacelles not equipped with thrust inverters, so-called smooth nacelles, and comprising cowls which may be opened allowing access to the inside of the nacelle in the same way, as well as to other maintenance cowls fitting out the nacelle.
Such electric systems for detecting locking are known which give the possibility of ensuring a visual inspection of the situation. Such a system however requires an electric power supply source and is subject to possible electrical failures.
One of the difficulties of a mechanical system is however to ensure that the unlocking indicator actually displays an unlocking status as soon as the first lock is open, and conversely that this indicator can only switch to a locking status when strictly all the locks are locked.
Moreover, the existing mechanical systems are limited to checking the position of the handle of the lock, while the sought mechanical function is putting the locks under stress.